They left the Maryland Historical Society tucked inside the coat pockets and notebooks of Barry Landau and his assistant, but the historical documents returned in manila envelopes, neatly packed inside a gray cardboard file box.

Authorities continue to reunite more than 10,000 items "of cultural heritage" to museums and libraries along the East Coast that were targeted by Landau and his assistant Jason Savedoff. This month the Maryland Historical Society has received about one-third of 60 documents stolen.

It was there that employees first became suspicious of Landau, who was sentenced last June to seven years in federal prison for the theft of thousands of historical documents, and Savedoff, who received a one-year sentence.

"My library looked like a crime scene," recalled Patricia Dockman Anderson, director of publications and library services at the Maryland Historical Society. "I never thought it would be anything of that magnitude."

Almost two years after the two men were apprehended, investigators with the Federal Bureau of Investigation and the National Achieves and Records Administration are still trying to return to their rightful owners the items that had been collected as evidence.

About 20 percent of the documents have been returned, authorities said. Investigators hope to have the remaining items returned in coming months.

"All of the items have been associated with a victim; we just need to physically transport them to their homes," FBI Special Agent Matt Kazlauskas said in an email.

Landau and Savedoff took from numerous museums, including the Historical Society of Pennsylvania, the University of Vermont and the Franklin D. Roosevelt Presidential Library. They sold some of the items taken from the Roosevelt library, including copies of the president's inauguration speeches, for more than $46,000.

At the Connecticut Historical Society in Hartford, where Landau and Savedoff spent four days making off with several hundred items, Richard C. Malley, head of Research and Collections, said the majority of those items have been returned.

However, Malley said records for some of the historical society's ephemera, or memorabilia such as programs and tickets for noteworthy events, are not as detailed as those for more significant documents.

"Whether we got 100 percent, I don't think we can say," he said of the prospect for recovering all of the memorabilia.

"We count ourselves fortunate that we did get back most, if not all the material that was taken," Malley said, including original, one-of-a kind documents such as a letter from George Washington to Treasury Secretary Oliver Wolcott, Jr. and another letter for Marie Antoinette.

"It was a painstaking and very difficult process," for investigators, he said.

Among the items recently returned to the Maryland Historical Society on Monument Street were a 1920 Democratic National Convention ticket stub and admission passes to Andrew Johnson's impeachment. Each document was encased by clear Mylar, carefully placed inside the envelopes and categorized by four-digit penciled numbers by investigators.

In a folder marked number 2977 from Box 22 and dated 8/12/11 was a small, index card-size ticket that read "Admit the bearer May 26th 1868," to the gallery for Andrew Johnson's impeachment. But on the back was a new mark, Savedoff's small, penciled mark "W2," which stood for "Weasel 2." Landau referred to himself as "Weasel 1," according to court documents.

Another folder held a narrow, white piece of paper with elegant cursive detailing Lincoln's funeral procession in Vermont.

The oldest document stolen from the library by Landau and Savedoff was an invitation for the "Baltimore Assembly" dance, held on Nov. 5, 1793.

Dockman Anderson said the Maryland Historical Society is lucky to have nearly 100 percent of the stolen items recovered. "They really didn't have time to get rid of stuff" by selling them, she said.

The thieves came twice to Baltimore — first on June 15, 2011, and, again on July 9, 2011. It was on the second trip that they were foiled.

At a wooden table in the second floor reading room at the historical society, Dockman Anderson said Landau and Savedoff sat opposite of where the archivists sat. They hunkered down behind opened laptops, and were able to quietly stuff documents into their coat pockets or shuffle them into their own stacks of papers.

They brazenly used nail files to remove items from scrapbooks, or as they referred to it, "perform surgery," court documents said. In some cases, they removed inventory markings "by applying sandpaper and other abrasive materials to the document," the documents said.

In addition to marking documents with either a W1 or a W2, Dockman Anderson pointed to several where "shoot" had been scrawled, which she said was code for "steal it."

At one point, Landau had offered cupcakes to employees at the archivists desk. But one employee, suspicious of the men, walked along the balcony overlooking the reading room and spotted Savedoff swiping a text, prompting employees to call police.

One of the items they tried unsuccessfully to make off with was a land grant signed by Abraham Lincoln to a former member of the Maryland militia who served in the War of 1812, which prosecutors had valued at $100,000.

"This is where our crackerjack Saturday crew caught these guys," Dockman Anderson said, as she pointed to the table.

No one has yet requested to view the pilfered documents, Dockman Anderson said. They still remain in the cardboard box investigators used to transport them. Investigators released the items to Dockman Anderson after marking them off on long spreadsheet, she said.

Staff now vigilantly checks guests' folders and notebooks, while other staff make careful checks around the room, searching for any unusual behavior. The chairs at the far end of the table have been removed and patrons are no longer permitted to sit there, nor wear long, bulky jackets inside the reading room, she said.

"We're all a little vigilant," Dockman Anderson said.

She commended investigators for the headway they've made in returning the items. "It's a mammoth, mammoth job."